1. Field
The present disclosure relates generally to antennas and, in particular, to managing the performance of antennas. Still more particularly, the present disclosure relates to a method and apparatus for managing side lobe levels for antennas.
2. Background
Typically, an antenna comprises one or more antenna elements electrically connected to at least one of a transmitter and a receiver. An antenna element is an electrical device that converts electrical signals into electromagnetic radiation and electromagnetic radiation into electrical signals. For example, an antenna may be configured to convert electrical signals received from a transmitter into electromagnetic radiation for transmission by the antenna. Further, an antenna may be configured to convert electromagnetic radiation received at the antenna into electrical signals to be sent to a receiver.
In some cases, the amplitudes and/or phases of the respective electrical signals being received at or sent from the different antenna elements in the antenna may be varied to change a radiation pattern of the antenna. The radiation pattern of an antenna describes the directional dependence of the strength of the electromagnetic radiation transmitted by the antenna or the sensitivity of the antenna to electromagnetic radiation received by the antenna.
Typically, the radiation pattern for an antenna may be represented by “lobes” and “nulls” at various angles with respect to the antenna. As used herein, the term “lobe” refers to angular directions at which the strength of the electromagnetic radiation transmitted reaches a maximum. As used herein, the term “null” refers to angular directions at which the strength of the electromagnetic radiation falls to substantially zero.
The phases of the electrical signals being received at or sent from the antenna elements in an antenna may be varied to electronically steer the antenna in a particular direction. Electronically steering an antenna also may be referred to as beamforming. When an antenna is electronically steered in a particular direction, the lobe at this particular direction, referred to as the “main lobe”, is designed to be larger than the other lobes. The other lobes, referred to as “side lobes”, represent undesired electromagnetic radiation being transmitted or received in undesired directions.
In some cases, one or more antenna elements in an antenna may operate outside of selected parameters. When these one or more antenna elements operate outside of selected parameters, the side lobe levels of the radiation pattern for the antenna may increase more than desired. A side lobe level (SLL) for a side lobe of the radiation pattern for an antenna is the ratio, in decibels (dB), of the amplitude at the peak of the main lobe to the amplitude at the peak of the side lobe.
Therefore, it would be advantageous to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.